I'm pretty much against Galaxy. Yet I have tried it, and I think it is possible to consider its various features from a neutral angle, regardless. At least, I will try my very best here:

ACHIEVEMENTS
I think this is a pretty fun feature! It gives the player an incentive to strive for various strange goals. In FTL, in-game achievements are used to unlock new stuff in the game, and that works pretty well.
What I don't get is why this has to be locked to a client with me signed in with my profile. Players care about their own achievements only. Nobody is following their "Friends" achievements, except maybe really weird stalker types. As with FTL, this would work just as fine offline.
Likewise, the single player game Nex Machina is pretty much useless without Galaxy, since the high-score and unlocks are tied to the client.

GAME TIME TRACKING
I like this feature! But again, shouldn't require me to be constantly signed in.

CLOUD SAVING
Only really useful if the user doesn't have their own backup solution. This feature is built on the assumption that the user can't manage their own data.

SCREENSHOTS
Practical, but would be better to have a basic solution.

A NICE POLISHED INTERFACE
The Galaxy GUI are prettier than the default Windows icons. To me, it gives a feeling of comfort. I sort of feel that I am in a different "space" than the windows interface. Some middle ground between the Windows interface and playing.

THE FEELING OF BEING "CONNECTED"
Being "connected" can give a feeling of being connected, being part of something. I remember feeling *disappointed* when I discovered that a game I bought "just" gave me the installation files, and not a Steam code! I wish there were more studies on how our self-image is affected by our online identities - facebook profile, steam profile, and so on. (okay, this is way disjointed - sorry!)

OVERLAY
Allows you to be disturbed by useless crap whilst playing. To me, this sounds more like a bug than a feature. But I'm a bit of an introvert. I don't play games because I want to hang out with Friends.

AUTO-UPDATING GAMES
This is a really practical feature since some games push small updates constantly. Dangerous if you use mods, though. To download an update, I need to be connected with my profile, obviously. But this doesn't warrant the requirement of me being *constantly* connected.

RUNNING GALAXY WITHOUT BEING CONNECTED
I would truly love this feature if it wasn't implemented so horribly. Galaxy goes into aggressive nagware mode if you dare using it without being signed in. Also, some features that shouldn't require you to be signed in will be missing.

FINAL VERDICT
Eh, I dunno. I guess galaxy has some handy features. Yet, most can be acquired elsewhere, in versions that are not crippled by being limited to a closed ecosystem.

No mention of Rollback?

Actually, I would prefer not to have this feature, or at least have an option to disable it. I actually don't like it when save files store the play time and display it on the save/load screen. I am going to be nitpicky here, but this part of your post is built upon the assumption that the player goes by male pronouns. Replacing "his" by "their" (in both spots) would fix this issue.

Also, it should be "built", not "build".

Unfortunately giving my honest thoughts about most of that would get me banned :P

Settings->Features and uncheck the game time tracking box. Similar choices exist for most of the other options.

Oddly, it's the only appeal of Galaxy (and Steam), for me. If you have a game installed on mulitple devices, being able to resume playing on any of them without seeking, copying, transferring game saves is pretty convenient.

Actually, one of the things I find most interesting about achievements is how they also display the percentage of players that have been awarded any given achievement. It makes for fascinating case studies. Take "New Vegas" for instance. That game has, I believe, four different endings, depending on which faction you chose to align yourself with. The highest number of players beat the game by going the "Fuck tha police! I'm the master of my own destiny"-route, while the lowest number of players joined forces with the Legion. It's often said that players enjoy playing evil characters, and yet the Galaxy statistics would indicate the opposite.

You'll also learn how many players bothered with the lame-ass minigames, how many players managed to suffer through the whole length of the abysmal "Dead Money"-DLC, and so on and so forth. It's fascinating stuff.

I'm starting to lose track of all these 'my thoughts'/'why I like/dislike this thing GOG does/doesn't do' threads! Why are there so many recently, is it contagious?

Note: I'm not against these threads, there are just so many of them.

Thanks, corrected! (Lotsa web controversy about using 'they' in third person singular. It has a Wikipedia article too!)

Curiously, my mental draft said: "This feature is build of the assumption that the user isn't man enough to manage his own data." I think this had a stronger impact, but at the cost of being obviously bro-centric.

BTW, In Danish, we have the word "vedkommende" which functions as a "he/her" but it is a peculiar word that clearly telegraphs that vedkommende is intentionally avoiding specifying gender.

Anyways, thanks for getting me sidetracked!

Lolz... Eh, some of it has its use. However many of these features don't require an extra online client program... Or they shouldn't.

I think GOG is doing what they have to do to bring us new games. So far they haven't forced anything, and I think thats awesome. On a feature per feature breakdown I feel.........

*Multiplayer - Devs are making new games for Steam, dev's are easiy able to add MP to the GOG client for new games. Making this an option for us to play online. The GOG staff can't re-code the game without the MP client, if thats how the game was designed............So for newer games, its this or single player. Simple as that.

*Screenshots - Nice touch, would like to be able to remap the hotkey.

*Updating & Rollbacks - I keep "auto" turned off, and choose what to install. Very fast and simple. I like being able to Rollback the changes without re-installing the whole game.

*Cloud saves- Another good idea that needs a small tweek. I only want to use this on about 5% of my games, so if it was defaulted to "off" then you had to select per game, rather than turn them all off one by one, it would be more usefull to me.

*Achievements - Could care less, but I think some people like them, so its nice to see them available.

I only run the client for gaming Multiplayer on newer games, so about 20% of the time. I'm glad they are working towards staying current, and leeping it optional at the same time.

This feature needs to be added and then i'll be happy with it...

https://www.gog.com/wishlist/galaxy/set_launch_options_command_line_arguments_for_games

Wow, a whole long list of "features" I have no interest or use for.

The most convenient feature in my opinion. It's difficult for players to manage their save data because games often use obscure folders in various paths on the drive. There have been attempts to standardise the location, but game developers have their own ideas. Therefore automatic cloud updating is a hassle-free, practical solution.
This is your idea of fun? And here I was, trying actively to avoid bugs by patching my games. :P